The present invention relates to a cleaning method and system for cleaning an article with a solvent, and particularly but not exclusively relates to a cleaning method and system for cleaning an article, such as a metallic mold, a porous sintered metal and an integrated circuit substrate, using an organic solvent such as Freon (Tradename), trichloroethylene and the like substance.
Heretofore, cleaning systems using an organic solvent, such as Freon and trichloroethylene, are widely used for removing soil adhered to such an article to be cleaned. For cleaning the article, an airtight cleaning tank in which the article is to be placed is evacuated by a vacuum pump so that an organic solvent can easily soak to fine irregular surfaces and fine cavities of the article, and then the organic solvent is supplied from a solvent storing tank into the cleaning tank through a solvent supply pipe. After supplied, the organic solvent is oscillated by means of an ultrasonic oscillator or is agitated by agitating blades to remove soil, such as an oil, adhered to the surfaces of the article. When the article is not cleaned by a single operation, the organic solvent is discharged from the cleaning tank, which is then evacuated by the vacuum pump again. Thereafter, the organic solvent is reintroduced into the cleaning tank and then the article undergoes the cleaning operation. After accomplishing the cleaning, a solenoid valve of a drain pipe which connects the cleaning tank to the storage tank is opened and a draining pump, installed in the drain pipe, is activated to discharge the liquid organic solvent from the cleaning tank into the storage tank. Then, the article is taken out from the cleaning tank.
In the conventional cleaning system, leakage of part of vapor of the organic solvent to the atmosphere is inevitable in supplying and discharging of the organic solvent, and this can results in pollution of the environment. More specifically, the conventional cleaning system has a suction and exhaust pipe mounted to the top of the cleaning tank for communication to the atmosphere, and in addition a gas mixture of air and vapor of the organic solvent is present in an upper space of the storage tank. When the volume of the upper space of the storage tank is reduced by introducing the liquid organic solvent into the storage tank after the cleaning, the gas mixture in the upper space is discharged to the atmosphere through the suction and exhaust pipe, thus contaminating the environment. Particularly, leakage of Freon which is widely used as an organic solvent for cleaning should be as little as possible since it is reported that it will destroy the ozone layer, resulting in destruction of the global environment.
Accordingly, it is an object of the present invention to provide a cleaning method and system in which in cleaning, leakage of the solvent to the atmosphere is prevented with efficient use thereof, whereby the problem to prevent pollution of the environment with the solvent is solved.